U.S. patent application number 13/130212 was filed with the patent office on 2011-11-24 for polyamide and bioresourced reinforcement compositions having improved mechanical properties.
This patent application is currently assigned to Arkema France. Invention is credited to Benoit Brule, Philippe Bussi, Gilles Hochstetter, Guillaume Le, Barbara Ramfel.
Application Number | 20110288194 13/130212 |
Document ID | / |
Family ID | 40688451 |
Filed Date | 2011-11-24 |
United States Patent
Application |
20110288194 |
Kind Code |
A1 |
Brule; Benoit ; et
al. |
November 24, 2011 |
POLYAMIDE AND BIORESOURCED REINFORCEMENT COMPOSITIONS HAVING
IMPROVED MECHANICAL PROPERTIES
Abstract
One subject of the present invention is a composition that
combines at least one polyamide having at least one MXD entity, MXD
denoting meta-xylylenediamine or a mixture of meta-xylylenediamine
and of para-xylylenediamine, with a bioresourced reinforcement. The
invention also relates to the conversion of these compositions, by
injection moulding or extrusion, into objects that have good
mechanical properties, said objects corresponding to technical
application specifications such as may be found, for example, in
the automotive industry, construction, sport and in electrical or
electronic fields.
Inventors: |
Brule; Benoit;
(Beaumont-le-Roger, FR) ; Bussi; Philippe;
(Versailles, FR) ; Hochstetter; Gilles; (Bernay,
FR) ; Le; Guillaume; (Colombelles, FR) ;
Ramfel; Barbara; (Barc, FR) |
Assignee: |
Arkema France
Colombes
FR
|
Family ID: |
40688451 |
Appl. No.: |
13/130212 |
Filed: |
November 23, 2009 |
PCT Filed: |
November 23, 2009 |
PCT NO: |
PCT/FR2009/052260 |
371 Date: |
August 5, 2011 |
Current U.S.
Class: |
522/2 ; 156/192;
156/308.2; 264/141; 264/164; 522/176; 524/35; 524/9 |
Current CPC
Class: |
B29C 48/15 20190201;
C08J 2377/00 20130101; C08G 69/26 20130101; C08L 77/06 20130101;
B29C 48/0017 20190201; B29C 70/46 20130101; B29C 48/154 20190201;
C08J 5/08 20130101; B29K 2105/06 20130101; C08J 5/06 20130101; B29C
48/001 20190201; C08G 69/36 20130101; C08J 5/24 20130101; B29L
2031/731 20130101; B29C 48/022 20190201; C08L 77/06 20130101; B29C
48/00 20190201; B29C 70/32 20130101; B29C 48/05 20190201; B29K
2311/10 20130101; C08J 2377/06 20130101; C08L 1/02 20130101; B29B
15/08 20130101; B29C 48/34 20190201; B29C 70/06 20130101; B29C
70/12 20130101; B29C 70/465 20130101; B29C 70/521 20130101; C08J
5/045 20130101 |
Class at
Publication: |
522/2 ; 524/35;
524/9; 522/176; 264/141; 156/308.2; 156/192; 264/164 |
International
Class: |
C08J 3/28 20060101
C08J003/28; C08K 11/00 20060101 C08K011/00; B29C 51/00 20060101
B29C051/00; B32B 37/04 20060101 B32B037/04; B32B 38/08 20060101
B32B038/08; C08K 5/06 20060101 C08K005/06; B29B 9/06 20060101
B29B009/06 |
Foreign Application Data
Date |
Code |
Application Number |
Nov 21, 2008 |
FR |
08.57931 |
Claims
1-28. (canceled)
29. A composition that combines at least one polyamide having at
least one MXD entity, MXD denoting meta-xylylenediamine or a
mixture of meta-xylylenediamine and of para-xylylenediamine, with a
natural reinforcement.
30. The composition as claimed in claim 29, characterized in that
the polyamide corresponds to the formula MXD.Z, the Z entity being
an aliphatic, cycloaliphatic or aromatic, C.sub.4-C.sub.36
dicarboxylic acid.
31. The composition as claimed in claim 29, characterized in that
the polyamide is a copolyamide corresponding to the formula
A/MXD.Z, the Z entity being an aliphatic, cycloaliphatic or
aromatic, C.sub.4-C.sub.36 dicarboxylic acid, and the A entity
being chosen from a lactam, an .alpha.,.omega.-aminocarboxylic acid
and the product of the reaction of an aliphatic, cycloaliphatic or
aromatic, C.sub.4-C.sub.36 dicarboxylic acid with an aliphatic,
cycloaliphatic, arylaliphatic or aromatic, C.sub.4-C.sub.36
diamine.
32. The composition as claimed in claim 30, characterized in that
the Z entity is an aliphatic dicarboxylic acid comprising at least
6, advantageously 7 and more preferentially 10 carbon atoms.
33. The composition as claimed in claim 31, characterized in that
the A entity is a lactam or an .alpha.,.omega.-aminocarboxylic acid
comprising at least 6, and more preferentially at least 10, carbon
atoms.
34. The composition as claimed in claim 33, characterized in that
the A entity is chosen from caprolactam, lactam 12,
11-aminoundecanoic acid and 12-aminododecanoic acid.
35. The composition as claimed in claim 31, characterized in that,
the A entity being the product of condensation of a diamine with a
dicarboxylic acid, said diamine is an aromatic diamine, preferably
meta-xylylenediamine or a mixture of meta-xylylenediamine and of
para-xylylenediamine.
36. The composition as claimed in claim 31, characterized in that
the molar proportion of the MXD.Z unit, in the copolyamide of
formula A/MXD.Z, represents more than 25%, preferably more than 50%
and more preferentially more than 65%.
37. The composition as claimed in claim 29, characterized in that
the natural reinforcement comprises at least one element chosen
from plant fibers, animal fibers, biobased polymers, biobased
carbon fibers and biobased carbon nanotubes.
38. The composition as claimed in claim 37, characterized in that
the plant fiber is chosen from flax, hemp, sisal, kenaf, abaca and
jute.
39. The composition as claimed in claim 29, characterized in that
the natural reinforcement is in the form of a ground material, a
flour, a short fiber, a long fiber, woven continuous fibers,
nonwoven continuous fibers, or a mat of woven or nonwoven
fibers.
40. The composition as claimed in claim 29, characterized in that
it also comprises at least one second reinforcement which is not
natural, it being possible for said second reinforcement to be a
carbon fiber, carbon nanotubes or glass fibers.
41. The composition as claimed in claim 40, characterized in that
the (natural reinforcement) to (non-natural second reinforcement)
mass ratio is greater than 0.3, preferably greater than or equal to
1, and more particularly greater than or equal to 3.
42. The composition as claimed in claim 29, characterized in that
the weight proportion of natural reinforcement and, where
appropriate, of non-natural second reinforcement is between 5% and
80%, advantageously between 10% and 70%, preferably between 15% and
50%, and even more preferably between 15% and 40%, of the total
weight of the composition.
43. The composition as claimed in claim 29, characterized in that
it also comprises at least one second polyamide.
44. The composition as claimed in claim 43, characterized in that
the weight proportion of the second polyamide represents less than
50%, preferably less than 25%, and more particularly less than 15%,
of all of the polyamides.
45. The composition as claimed in claim 29, characterized in that
it also comprises at least one additive chosen from impact
modifiers, processing aids, UV-stabilizers, heat-stabilizers,
fire-retardants, preferably in a weight proportion representing
less than 50%, advantageously less than 20%, of the total weight of
the composition.
46. The composition as claimed in claim 29, characterized in that
it also comprises fillers, such as talc, montmorillonite, chalk,
mica and kaolin, preferably in a weight proportion representing
less than 30%, and more particularly less than 20%, of the total
weight of the composition.
47. The composition as claimed in claim 29, characterized in that
the natural reinforcement and, where appropriate, the non-natural
second reinforcement undergo a treatment aimed at improving their
adhesion with respect to the polyamides, said treatment being
chosen from: a chemical treatment, a precoating of the
reinforcement with a polymeric coupling agent, a plasma treatment,
a mechanical or thermomechanical treatment, a laser treatment, a
.gamma.- or UV-irradiation.
48. A method for producing a composite material from a composition
comprising a natural reinforcement in the form of short fibers as
claimed in claim 39, said method comprising the following steps:
A--compounding of the natural reinforcement and of the polyamide(s)
in an extruder or a co-kneader, between 180 and 240.degree. C.,
B--extrusion of the rod, C--granulation of the rod.
49. A method for producing a composite material from a composition
comprising a natural reinforcement in the form of long fibers as
claimed in claim 39, said method comprising the following steps:
A--impregnation of the natural reinforcement in the molten
polyamide(s) between 180 and 240.degree. C. by means of a crosshead
extruder, B--extrusion of the rod, C--granulation of the rod.
50. A method for producing a composite material from a composition
comprising a natural reinforcement in the form of woven or nonwoven
fibers as claimed in claim 39, said method comprising the following
steps: A--stacking of alternating natural reinforcement and films
of the polyamide(s), or rolling of natural reinforcement
multilayers alternating with a film of polyamide(s),
B--hot-pressing of between 180 and 240.degree. C.
51. A method for producing a composite material from a composition
comprising a natural reinforcement in the form of continuous fibers
as claimed in claim 39, said method comprising the following steps:
A--preimpregnation of the natural reinforcement in a fluidized bed
of polyamide(s) by the electrostatic route and then heating in an
oven brought to between 200.degree. C. and 240.degree. C., or in
the molten polyamide(s), B--filament winding, C--heating in an oven
brought to between 180.degree. C. and 240.degree. C.
52. A method for producing a composite material from a composition
comprising a natural reinforcement in the form of woven or nonwoven
fibers as claimed in claim 39, said method comprising the following
steps: A--preimpregnation of the natural reinforcement,
B--production of sheets by hot-pressing of between 180 and
240.degree. C.
53. A method for producing a composite material from a composition
comprising a natural reinforcement in the form of continuous fibers
as claimed in claim 39, for producing profiles by pultrusion, said
method comprising the following steps: A--drawing of the natural
reinforcement and continuous impregnation of the polyamide(s) in a
molten state or in a fluidized bed of powder of polyamide(s),
B--passing through a heating fixture brought to between 180 and
240.degree. C. giving the shape of the cross section of the
profile.
54. The use of a composition as claimed in claim 29, for producing
objects, in particular a recyclable object.
55. An object obtained from a composition according to claim 29, in
particular by injection-molding, extrusion, forming, calendering,
filament winding or pultrusion of such a composition.
56. The use of the object as claimed in claim 55 in the automotive
field, the construction field, in the electrical or electronic
field, or in the sporting goods field.
Description
[0001] The subject of the present invention is a composition based
on polyamide(s) which may or may not be partially biobased, at
least one polyamide having at least the MXD unit, said composition
comprising biobased or natural reinforcements. The invention also
relates to the conversion of this composition into objects which
have good mechanical properties and which make it possible to meet
technical application specifications such as may be found, for
example, in the automotive industry, construction, the sporting
goods field and the electrical or electronic fields.
[0002] At the current time, in the field of materials based on
thermoplastic matrices, no combination exists with natural
reinforcements having technical properties sufficient for certain
applications that require good rigidity, good thermomechanical
strength and good resistance to aging. Moreover, the matrices that
it would be desired to combine with these natural reinforcements do
not generally have a transformation temperature range which is
compatible with the incorporation of such thermosensitive natural
reinforcements. It is known that the major constituents of natural
reinforcements, such as lignin, hemicellulose and pectins, are
particularly thermally sensitive, others, such as
.alpha.-cellulose, being on the other hand less so.
[0003] The term "natural reinforcements" is intended to mean, for
example, wood meals, short or long plant fibers (flax, hemp, kenaf,
abaca, etc.), continuous fibers, mats resulting from these
fibers.
[0004] Moreover, there is an increasing interest in materials which
result from biobased starting materials, due in particular to the
exhaustion of starting materials of fossil origin, which at the
same time retain effective usage properties.
[0005] Biobased or natural reinforcements are materials which
furthermore generally have a density lower than that of inorganic
reinforcements, and they are less abrasive with respect to
transformation tools compared with inorganic reinforcements.
Natural reinforcements are, moreover, inexpensive and consume less
energy for their production in comparison, for example, with glass
fibers.
[0006] On the other hand, biobased or natural reinforcements
generally exhibit poor adhesion with respect to polymeric matrices
such as polyamides. In certain cases, they must be surface-treated,
in order to improve their adhesion with respect to these matrices,
with coupling agents, additives, or treatments such as plasma,
corona, laser, .gamma.- or UV-irradiation, chemical, mechanical, or
thermal treatments or the like.
[0007] Polyamides forming the subject of this invention, which can
be partially biobased, correspond in particular to the formula
A/MXD.Z with Z denoting an entity originating from a diacid and A,
when it is present, denoting an entity which can originate from an
amino acid, preferably 11-amino, from a lactam, such as lactam-12
or from the X.Y product of reaction of a diamine X and of a
dicarboxylic acid Y. This X.Y entity will preferably be biobased,
and will correspond, for example, to the entity 10.10, 10.12 or
6.10. The MXD entity, for its part, denotes meta-xylylenediamine or
a mixture of meta-xylylenediamine (MXD) and of para-xylylenediamine
(PXD), meta-xylylenediamine preferably being predominant in said
mixture.
[0008] The use of biobased or natural reinforcements involves
converting these compositions at temperatures, measured in said
compositions in the molten state, which are moderate (typically
less than 215.degree. C.), even for short residence times
(approximately 2 minutes). The thermoplastic matrix based on
polyamide(s) should thus have a transformation temperature range
that is compatible with the incorporation of thermosensitive
natural reinforcements in order to provide good wetting of the
fibers, without degrading them. This can be obtained by judicially
selecting the monomers of the matrix based on polyamide(s), but
also by the addition of a compound such as stearic acid or lithium
salts, as described in document US 2004/0122133.
[0009] The present invention is not limited to only biobased or
natural reinforcements. In addition to the natural reinforcements,
the use of fibers, mineral tissues (glass, carbon, etc.) or fillers
(talc, montmorillonite, etc.) can also be envisioned in order to
finely adjust the properties, in particular the mechanical
properties.
[0010] The compositions of the present invention may also contain
additives, such as coupling agents, which may be polymeric, impact
modifiers, processing aids, UV- and/or heat-stabilizers,
fire-retardants such as, in particular, Mg(OH).sub.2, Al(OH).sub.3
and phosphinates.
[0011] The matrices of these compositions exhibit good rigidity,
typically a tensile modulus of 2 GPa at least after
conditioning.
PRIOR ART
[0012] Document EP 0 272 503 describes matrices of MXD.10 type
(poly(m-xylylenesebacamide)) combined with a semicrystalline
polyamide. These matrices can contain glass fibers. The combination
of a second polymer having a melting point from 20 to 30.degree. C.
above that of the MXD10 does not allow the combination of natural
fibers as there would be a risk of said natural fibers being
degraded. In addition, the fibers used are not biobased or
natural.
[0013] Document WO 2007/137378 describes compositions based on
polyamides (including PA6 in particular) and on natural fibers such
as curaua fiber. In said document, the biobased nature is provided
only by the natural fiber, the matrix being of fossil origin. Said
document does not refer to particular difficulties in incorporating
the thermosensitive natural fibers into the PA6. Moreover, it is
not indicated whether the reported value (5100 MPa) of the tensile
modulus of a PA6-curaua fibers mixture (80/20 proportion by weight)
is obtained before or after conditioning of the polyamide.
[0014] As it happens, the technical documents of PA6 producers all
indicate that the tensile modulus of PA6 varies very considerably
between the dry state (i.e. on exiting the injection cycle) and the
conditioned state (i.e. after 15 days spent at 23.degree. C. and at
50% relative humidity). These technical documents indicate that, on
average, the tensile modulus of PA6 in the dry state is of the
order of 3000 to 3400 MPa, whereas it is only 900 to 1200 MPa after
conditioning. In order to assess the mechanical performance of
compositions based on PA6 and on natural reinforcements under
conditions of use, it is therefore essential to test
pre-conditioned samples.
[0015] U.S. Pat. No. 6,270,883 describes compositions based on PA6
and on wood cellulosic fibers, optionally containing coupling
agents in order to improve mechanical performance. Here again, the
matrix (PA6) is of fossil origin. These PA6-wood cellulosic fiber
compositions (70/30 proportion by weight) have tensile moduli of
between 5350 and 5700 MPa in the presence of 2% by weight of
coupling agent, and between 5100 and 5200 MPa without coupling
agent, the PA6 matrix having a tensile modulus of 2750 MPa.
However, these performance levels are measured in the dry state.
Moreover, the wood cellulosic fibers producing these results were
chosen for their higher thermal stability, since they contain at
least 95% by weight of .alpha.-cellulose, and therefore less than
5% by weight of thermosensitive components such as lignin or
hemicellulose.
[0016] Document US 2004/122133 describes compositions based on PA6
and on biobased or natural fibers, and also a method for obtaining
these compositions, characterized in that a lithium chloride (LiCl)
salt is introduced beforehand into the PA6 matrix in order to
substantially lower the melting point thereof, which goes from
223.degree. C. to, respectively, 199.degree. C. or 194.degree. C.
according to the amount of LiCl added (respectively 3.0% and 3.5%
by weight). Thermosensitive natural fibers can therefore be
introduced, without risk of degradation, into the PA6/LiCl matrix
in the molten state since the polymer can be converted at lower
temperatures. However, this process has the drawback of even
further promoting the propensity of PA6 to take up moisture again
since the salts selected are hydrophilic. The compositions
according to the invention do not require the melting point of the
polyamide matrix to be lowered.
[0017] Documents JP 2005-060556 and US 2006/0202391 describe the
combination of PLA (polylactic acid a priori biobased) and kenaf
fibers. Now, PLA is difficult to transform in the presence of water
since it is an aliphatic polyester. Moreover, PLA is more sensitive
to water than polyamides, which means that a perfectible aging
behavior can be envisioned.
[0018] Document WO 2008/050568 describes compositions based on PA11
and on natural fibers, such as flax, hemp, bamboo or silk. These
compositions are biobased but do not result in sufficient
mechanical properties, in particular in terms of tensile modulus,
owing to the presence of PA11.
[0019] Document EP 0 711 324 describes a composition of
biodegradable polymer reinforced with natural fibers. The
biodegradable polymer is starch which has limited mechanical
properties and a high sensitivity to water, thus limiting its value
for use.
[0020] Document EP 0 960 162 discloses, in example 9 thereof, a
method for obtaining a composition based on PA11 and containing 25%
by volume of flax fibers, which corresponds to 33% by weight of
fibers given the density of PA11 (1.03) and that of flax fibers
(1.50). This composition is characterized in particular by a
tensile modulus of 4050 MPa (according to standard DIN 53455). It
should be noted that, contrary to PA6, the tensile modulus of PA11
is less sensitive to conditioning. The composition described is
biobased but does not result in sufficient mechanical properties,
in particular in terms of tensile modulus.
[0021] The applicant has noted that the combination of at least one
polyamide, which may be partially biobased and which contains at
least one MXD entity, with biobased or natural reinforcements can
make it possible to obtain materials having good usage properties.
This polyamide containing an MXD entity exhibits, moreover, a
transformation temperature range compatible with the incorporation
of thermosensitive natural fibers.
SUMMARY OF THE INVENTION
[0022] The invention relates to a composition that combines at
least one polyamide having at least one MXD entity, MXD denoting
meta-xylylenediamine (MXD), or a mixture of meta-xylylenediamine
(MXD) and of para-xylylenediamine (PXD), with one or more biobased
reinforcements, the term "biobased" being understood within the
meaning of standard ASTM D6852, and more preferentially within the
meaning of standard ASTM D6866.
[0023] Standard ASTM D6852 indicates the proportion of products of
natural origin in the composition, while standard ASTM D6866
specifies the method and the conditions for measuring the renewable
organic carbon, i.e. which derives from biomass.
[0024] The reinforcement(s) of the composition according to the
invention are termed biobased, i.e. it (they) comprise(s) organic
carbon derived from biomass and determined according to standard
ASTM D6866. In such a case, it may be considered that the
composition according to the invention is itself partially
biobased, which is an advantage compared with compositions based on
non-biobased fibers, for example derived from fossil starting
materials.
[0025] The invention also relates to methods for producing a
composite material from such a composition, the methods for
obtaining objects from the compositions of the invention and also
the objects and the use of the compositions and objects of the
invention.
[0026] Admittedly, a composition which contains a biobased
polyamide containing natural fibers is known from document WO
00/59989. However, it does not appear, on reading this prior art,
to be obvious for those skilled in the art to choose a PA based on
MXD and to combine it with biobased reinforcements, in order to
obtain a material which has good mechanical properties and which
can be transformed at temperatures limiting degradation of the
natural fibers. In said document, aliphatic diamines are preferred
and exemplified, unlike the MXD which forms the subject of the
invention.
DETAILED DESCRIPTION
[0027] As a preamble, it is specified that the expression "between"
used in the rest of this description should be understood as
including the limits cited.
[0028] The term "MXD" is understood to mean meta-xylylenediamine or
a mixture of meta-xylylenediamine (MXD) and of para-xylylenediamine
(PXD). Preferentially, MXD diamine will be predominant in the
mixture. This MXD and/or PXD diamine is commonly produced from
resources of fossil origin.
[0029] The term "biobased" is understood within the meaning of
standard ASTM D68652, and more preferentially within the meaning of
standard ASTM D6866, as indicated above.
[0030] The term "conditioning" is intended to mean residence of the
material for 15 days at 23.degree. C. at a relative humidity of
50%.
[0031] The term "reinforcement" is intended to mean short or long
fibers, woven or nonwoven continuous fibers, a woven or nonwoven
mat, or else ground materials, flours, which allow the tensile
modulus to be increased when they are combined with polymeric
matrices.
[0032] The composition according to the invention comprises at
least one polyamide, said polyamide having at least one MXD
entity.
[0033] According to a first variant of the invention, this
polyamide is a homopolyamide which corresponds to the formula
MXD.Z, the MXD entity being as defined above and the Z entity being
an aliphatic, cycloaliphatic or aromatic, C.sub.4-C.sub.36
dicarboxylic acid.
[0034] According to a second variant of the invention, this
polyamide is a copolyamide corresponding to the formula A/MXD.Z, in
which: [0035] the MXD entity is as defined above, [0036] the Z
entity is an aliphatic, cycloaliphatic or aromatic,
C.sub.4-C.sub.36 dicarboxylic acid, and [0037] the A entity is
chosen from a lactam, an .alpha.,.omega.-aminocarboxylic acid and
the product of the reaction of an aliphatic, cycloaliphatic or
aromatic, C.sub.4-C.sub.36 dicarboxylic acid with an aliphatic,
cycloaliphatic, arylaliphatic or aromatic, C.sub.4-C.sub.36
diamine.
[0038] Preferably, the weight proportion of the MXD.Z unit, in the
copolyamide of formula A/MXD.Z, represents more than 50%,
preferably more than 75% and more preferentially more than 85%.
[0039] Otherwise worded, the molar proportion of the MXD.Z unit, in
the copolyamide of formula A/MXD.Z, represents more than 25%,
preferably more than 50% and more preferentially more than 65%.
[0040] Whether in the context of the first or the second variant of
the invention, the Z entity may be an aliphatic dicarboxylic acid
comprising at least 6, advantageously 7 and more preferentially 10
carbon atoms.
[0041] Thus, Z may be an aliphatic diacid of formula
HOOC--(CH.sub.2).sub.y--COOH with (y+2)=4, 6, 7, 8, 9, 10, 12, 14,
16, 18.
[0042] A and/or Z correspond to a preferably biobased entity.
[0043] When A is present, it may be obtained from a lactam monomer
(in particular caprolactam or lauryllactam), an
.alpha.,.omega.-aminocarboxylic acid (such as 6-aminohexanoic acid,
10-aminodecanoic acid, 11-aminoundecanoic acid or else
12-aminododecanoic acid) or the product of reaction between a
dicarboxylic acid and a diamine.
[0044] The following may in particular be envisioned: [0045]
saturated or unsaturated, preferably linear, aliphatic diamines
chosen, for example, from butanediamine, pentanediamine,
hexanediamine, heptanediamine, nonanediamine, decanediamine,
undecanediamine, dodecanediamine, tridecanediamine,
tetradecanediamine, hexadecanediamine, octadecanediamine,
octadecenediamine, eicosanediamine, docosanediamine and diamines
obtained from fatty acids, [0046] aromatic or arylaliphatic
diamines, such as, for example, MXD and PXD (para-xylylenediamine),
[0047] cycloaliphatic diamines, such as, for example, isophorone
diamine, piperazine, 1,3-bisaminomethylcyclohexane or
bis(methylaminocyclohexyl)methane (BMACM), [0048] saturated or
unsaturated, preferably linear, aliphatic diacids chosen, for
example, from succinic acid, adipic acid, heptanedioic acid,
azelaic acid, sebacic acid, undecanedioic acid, dodecanedioic acid,
brassylic acid, tetradecanedioic acid, hexadecanedioic acid,
octadecanoic acid, octadecenoic acid, eicosanedioic acid,
docosanedioic acid and dimers of fatty acids containing 36 carbons,
[0049] aromatic or arylaliphatic diacids, such as, for example,
isophthalic acid, terephthalic acid, 2,6-naphthalenedicarboxylic
acid (NDCA) or furandicarboxylic acid, [0050] cycloaliphatic
diacids, such as, for example, 1,4-cyclohexanedicarboxylic acid
(CHDA).
[0051] When the polyamide corresponds to the formula A/MXD.Z, the A
entity may be a lactam or an .alpha.,.omega.-aminocarboxylic acid
comprising at least 6, and more preferentially at least 10, carbon
atoms.
[0052] Advantageously, the A entity is chosen from caprolactam,
lactam 12, 11-aminoundecanoic acid and 12-aminododecanoic acid.
[0053] In the case where the A entity is the product of
condensation of a diamine with a dicarboxylic acid, said diamine is
an aromatic diamine, preferably meta-xylylenediamine or a mixture
of meta-xylylenediamine and of para-xylylenediamine.
[0054] The choices of A and Z are preferably made such that: [0055]
A and/or Z are of partially or totally biobased origin, [0056] the
melting point of the (co)polyamide is less than or equal to
215.degree. C. (measured by DSC--ramp of 20.degree.
C./min--according to standard ISO 11357-3 (1999)), [0057] the
tensile modulus of the (co)polyamide is greater than or equal to
2000 MPa (measured according to standard ISO 527 1BA on conditioned
samples).
[0058] Preferably, the following polyamides will be favored: MXD.Z
with Z being suberic acid, azelaic acid, sebacic acid,
dodecanedioic acid or tetradecanedioic acid. More preferably, Z is
sebacic acid. Sebacic acid is commonly obtained from castor oil,
which is obtained from the plant of the same name.
[0059] Preferably, the following copolyamides will be favored:
[0060] A/MXD.Z with A being 11-aminoundecanoic acid or
10-aminodecanoic acid, Z being adipic acid, sebacic acid or
dodecanedioic acid. More preferably, Z is adipic acid and A is
11-aminoundecanoic acid. 11-Aminoundecanoic acid is commonly
obtained from castor oil, which is obtained from the plant of the
same name; [0061] A/MXD.Z, with A being caprolactam or lactam 12, Z
being adipic acid, sebacic acid or dodecanedioic acid. More
preferably, Z is adipic acid; [0062] A/MXD.Z with A being the
product of condensation of a dicarboxylic acid and a diamine, Z
being adipic acid, sebacic acid or dodecanedioic acid. Preferably,
the dicarboxylic acid of A is chosen from adipic acid, sebacic
acid, dodecanedioic acid, isophthalic acid and terephthalic acid.
Preferably, the diamine is chosen from hexamethylenediamine,
decanediamine, dodecanediamine and MXD. The decanediamine is
commonly obtained by amination and then hydrogenation of sebacic
acid, itself commonly obtained from castor oil.
[0063] When it may prove to be necessary, it is not out of the
question to mix the MXD-based polyamide with another polyamide or
copolyamide.
[0064] Thus, the composition according to the invention may also
comprise at least one second polyamide, it being possible for the
latter to be a homopolyamide or a copolyamide.
[0065] The proportion by weight of this other polyamide or
copolyamide (relative to all the polyamides present in the
composition) is less than 50%, preferably less than 25%, more
preferably less than 15%.
[0066] The first and/or second polyamide(s) of the composition may
be totally or partially biobased, i.e. comprise organic carbon
derived from biomass and determined according to standard ASTM
D6866. Thus, the biobased nature of the composition as a whole is
further reinforced.
[0067] The biobased reinforcement of the composition according to
the invention comprises at least one element chosen from plant
fibers or flours, animal fibers, biobased polymers, biobased carbon
fibers and biobased carbon nanotubes, the term "biobased" always
being understood within the meaning of standard ASTM D6852, and
more preferentially within the meaning of standard ASTM D6866.
[0068] A mixture of two, or more, reinforcements of the same
category or of different categories can of course be envisioned in
the context of the present invention.
[0069] The biobased reinforcements with which the invention is
concerned may be: [0070] plant fibers or flours which comprise
fibers or flours originating from the seminal hairs of seeds
(cotton, kapok), bast fibers or flours extracted from plant stems
(flax, hemp, kenaf, jute, ramie, etc.), hard fibers or flours
extracted from leaves (sisal, abaca, etc.), from trunks (Manilla
hemp, wood in general), from husks of fruits (coconut, etc.),
[0071] animal fibers which originate from hairs, such as animal
fleece, and secretions such as silk, [0072] carbon fibers or carbon
nanotubes derived from biobased starting materials, [0073]
polymeric fibers obtained from biobased materials, [0074] ground
materials from barks, peels or pips (hazelnuts, walnuts, etc.),
from animal shells (crabs, etc.), from grains (rice, etc.).
[0075] Preferably, the invention is concerned with plant fibers,
and more particularly, flax, hemp, sisal, kenaf, abaca or jute
fibers.
[0076] Preferentially, the biobased reinforcement, whether it
consists of just one or several of the elements detailed above,
represents from 5% to 50%, preferably from 15% to 40% by weight of
the total weight of the composition.
[0077] In one particular version of the invention, when the
biobased reinforcement is made up of nanotubes of biobased origin,
the weight ranges may be reduced in such a way that this
reinforcement represents from 2% to 20% by weight of the total
weight of the composition according to the invention.
[0078] In one advantageous version of the invention, the biobased
reinforcement is in the form of a ground material, of a flour, of a
short fiber, of a long fiber, of woven continuous fibers, of
nonwoven continuous fibers, or of a mat of woven or nonwoven
fibers.
[0079] The invention also concerns woven or nonwoven, continuous
biobased fibers, and biobased tissues (woven or nonwoven mats
obtained using these fibers or combinations of these fibers).
[0080] When necessary, it is not out of the question to add
non-biobased reinforcements such as carbon fibers or carbon
nanotubes of fossil origin, glass fibers, etc., in addition to the
biobased reinforcement, or else fillers such as talc, chalk, mica,
kaolin or montmorillonite.
[0081] Thus, the composition according to the invention may also
comprise at least one second reinforcement which is not biobased
within the meaning of standard ASTM D6852, and more preferentially
within the meaning of standard ASTM D6866, it being possible for
said second reinforcement to be a carbon fiber, carbon nanotubes or
glass fibers.
[0082] Preferentially, the weight proportion of all the
reinforcements, namely of the biobased reinforcement(s) and, where
appropriate, of the non-biobased reinforcement(s), is between 5%
and 80%, advantageously between 10% and 70%, preferably between 15%
and 50%, and even more preferably between 15% and 40%, of the total
weight of the composition.
[0083] Advantageously, the (biobased
reinforcement(s))/(non-biobased reinforcement(s)) mass ratio is
greater than 0.3, preferably greater than or equal to 1, and more
particularly greater than or equal to 3.
[0084] Preferably, these other non-biobased reinforcements
represent less than 30% and more particularly less than 20% by
weight of the total weight of the composition according to the
invention.
[0085] It is also sometimes necessary to modify the reinforcements,
in particular the fibers, of the composition according to the
invention by means of an appropriate treatment for improving the
adhesion of these reinforcements to the matrix.
[0086] Thus, the biobased reinforcement and, where appropriate, the
non-biobased second reinforcement may undergo a treatment aimed at
improving their adhesion with respect to the polyamides, said
treatment being chosen from: [0087] a chemical treatment, [0088] a
precoating of the reinforcement with a polymeric coupling agent,
[0089] a plasma treatment, [0090] a mechanical or thermomechanical
treatment, [0091] a laser treatment, [0092] a .gamma.- or
UV-irradiation.
[0093] Thus, chemical treatments such as the use of aminosilanes,
precoating of the fibers with a polymeric coupling agent, plasma,
laser, .gamma.-irradiation or UV-irradiation treatment, or another
chemical or mechanical treatment for improving the adhesion of
these reinforcements, in particular in the form of fibers, to the
matrix may be considered. In certain cases, a basic treatment
(sodium hydroxide), optionally followed by washing with water, may
be used in order to eliminate certain surface compounds, thus
allowing better coupling.
[0094] Moreover, the compositions of the present invention may also
contain one or more additives, such as coupling agents, which may
be polymeric, impact modifiers, processing aids, UV-stabilizers,
heat-stabilizers, fire-retardants such as in particular
Mg(OH).sub.2, Al(OH).sub.3 and phosphinates. The coupling agents
targeted herein are intended to improve the adhesion of the
reinforcements to the polyamide(s).
[0095] These additives generally represent less than 50% by weight,
preferably less than 30% by weight, of the total weight of the
composition.
[0096] For the coupling agents, impact modifiers, processing aids,
UV-stabilizers and heat-stabilizers, the content is in particular
less than 20% and preferably less than 10% by weight of the total
weight of the composition.
[0097] Finally, the composition according to the invention may also
comprise fillers such as talc, montmorillonite, chalk, mica and
kaolin, preferably in a weight proportion that can represent less
than 30%, and more particularly less than 20%, of the total weight
of the composition.
[0098] The compositions based on polyamides and on biobased
reinforcements according to the invention are characterized by a
tensile modulus in the conditioned state (measured according to
standard ISO 527 1BA on samples conditioned for 15 days at
23.degree. C. and at 50% relative humidity) preferably greater than
3500 MPa, more preferably greater than 5000 MPa.
[0099] These compositions may be used for the production of a
composite material from a composition comprising one (or more)
biobased reinforcement(s) in the form of short fibers, said method
comprising the following steps: [0100] A--compounding of the
biobased reinforcement and of the polyamide(s) in an extruder or a
co-kneader between 180 and 240.degree. C., in particular between
200 and 240.degree. C., for example 215.degree. C., [0101]
B--extrusion of the rod, [0102] C--granulation of the rod.
[0103] The objects of the invention are obtained: [0104] for a
biobased reinforcement in the form of short fibers, by injection
molding at 215.degree. C. (or injection compression) of granules of
short fibers, with the granule being obtained by compounding the
compositions of the invention on an extruder or co-kneader, between
180 and 240.degree. C., in particular between 200 and 240.degree.
C., for example at 215.degree. C., and cutting up the rod obtained;
[0105] for a biobased reinforcement in the form of long fibers, by
injection molding at 215.degree. C. (or injection compression) of
granules of long fibers, the granule being obtained by impregnating
bundles of continuous fibers in the molten polyamide between 180
and 240.degree. C., in particular between 200 and 240.degree. C.,
for example at 215.degree. C., by means of a cross-head extruder,
and then cutting up the rod obtained. The long fibers in the form
of a roving can also be incorporated directly during the injection
molding; [0106] for a biobased reinforcement in the form of woven
or nonwoven mats, obtaining stratified sheets via hot pressing at
between 180 and 240.degree. C., in particular between 200 and
240.degree. C., for example at 215.degree. C., of a stack of
alternating woven or nonwoven fiber mats and films of the
polyamide(s), or rolling of woven or nonwoven fiber mats onto a
film of polyamide(s); [0107] for a biobased reinforcement in the
form of fiber bundles, or a mat of fibers (woven or nonwoven),
production of preimpregnated materials obtained either by
impregnation (coating) of the fibers in a bath of molten polyamide
of between 180 and 240.degree. C., in particular between 200 and
240.degree. C., for example at 215.degree. C. (in the case of fiber
bundles, with a crosshead extruder), or by impregnation in a
fluidized bed (i.e. electrostatic powder coating and then melting
of the powder of polyamide(s) in an oven brought to between 180 and
240.degree. C., in particular between 200 and 240.degree. C. (for
example at 215.degree. C.), or by powder-coating and then
melt-coating at between 180 and 240.degree. C., in particular
between 200 and 240.degree. C., for example at 215.degree. C., and
then production of the composite from the preimpregnated materials,
either by filament winding (winding of the fiber bundles on a
mandrel), for the production of hollow bodies for example, or else
by pressing and thermoforming of sheets produced from the mats of
preimpregnated fibers, for the production of casings; [0108]
finally, for a biobased reinforcement in the form of fiber bundles,
production of the composite by pultrusion in order to produce
profiles (drawing of the fiber bundles and continuous impregnation
of the polyamide(s) in the molten state or in a fluidized bed and
passage through a heating fixture giving the shape of the cross
section of the profile), brought between 180 and 240.degree. C., in
particular between 200 and 240.degree. C., and for example at
215.degree. C.
[0109] Unless otherwise indicated, the temperature ranges which
have just been mentioned are those measured in the composition in
the molten state.
[0110] The objects obtained from the compositions according to the
invention may be components intended: [0111] for the nonlimited
automotive sector, such as cylinder-head cover, intake manifold,
radiator housing, [0112] for construction sectors, [0113] for
electrical or electronic sectors, such as housings, casings or
cabinets, [0114] for sporting goods sectors, such as, for example,
an element of shoes.
EXAMPLES
Examples 1 and 2
Nonreinforced MXD.10
[0115] ISO 527 1BA dumbbell-shaped specimens of polyamide MXD.10
synthesized from meta-xylylenediamine and sebacic acid having a
melt flow index (MFI) of 20 g/10 min at 275.degree. C. under 2.16
kg are injection-molded at 210.degree. C. in a mold maintained at
30.degree. C. or 120.degree. C. with a 60-tonne injection-molding
press. The granules of polyamide MXD.10 were predried at 60.degree.
C. for 12 hours in an oven under vacuum.
[0116] The melting point is measured by DSC according to standard
ISO11357.
[0117] The dumbbell-shaped specimens of MXD.10, but also of PA6 and
of PA11, are conditioned for 15 days at 23.degree. C. at a relative
humidity of 50%. The tensile properties are obtained with the
protocol described in standard ISO 527 1BA.
[0118] In table 1 hereinafter, the tensile moduli are compared
between MXD.10 injection-molded at 210.degree. C., polyamide-6
(PA6, Ultramid.RTM. 8202 sold by BASF) injection-molded at
260.degree. C. and polyamide-11 (PA11, Rilsan.RTM. BMNO TLD sold by
Arkema) injection-molded at 240.degree. C.
TABLE-US-00001 TABLE 1 Examples Comparative examples 1 2 A.sup.(1)
B.sup.(2) Polyamide MXD.10 MXD.10 PA6 PA11 T injection (.degree.
C.) 210 210 260 220-240 T mold (.degree. C.) 120-125 30-35 80 30-60
Melting point (.degree. C.) 193 193 220 187-191 Nonconditioned 3700
2700 2800 1260 tensile modulus (MPa) Conditioned tensile 3600 2550
970 1070 modulus (MPa) Density (g/cm.sup.3) 1.12 1.12 1.14 1.03 ISO
R1183 D
[0119] It is important to note that the PA MXD.10 is much less
sensitive to the conditioning (less water uptake) than PA6 since
the tensile moduli decrease by 2% to 6% for the PA MXD.10, whereas
for PA6, the modulus decreases by 66%. This advantage is
considerable especially when untreated natural reinforcements which
generally increase the water uptake of the compound are
introduced.
[0120] Furthermore, the PA MXD.10 can be injection-molded at
210.degree. C., whereas polyamide-6, for its part, is
preferentially injection-molded at 260.degree. C. and polyamide-11
at 240.degree. C.
[0121] It emerges from this comparison that it is necessary to take
into account the properties, in particular mechanical properties,
measured on samples which have been conditioned.
Examples 3 and 4 and Comparative Examples C to F
Polyamides with 15% by Weight of Reinforcements
[0122] Various compositions comprising 85% of a polyamide and 15%
by weight of reinforcements were prepared from the following
products:
[0123] The polyamides used are the following: [0124] the polyamide
MXD.10 (Mp of 193.degree. C.) is identical to that of examples 1
and 2; [0125] the polyamide 6 (denoted PA6, Mp of 220.degree. C.)
corresponds to the Ultramid.RTM. B3 commercial grade from the
company BASF; [0126] the polyamide 11 (PA11, Mp of 187-191.degree.
C.) corresponds to the Rilsan.RTM. BMNO grade from the company
Arkema France.
[0127] The melting points Mp mentioned above were measured by DSC
according to standard ISO 11357.
[0128] The non-biobased reinforcement is made up of glass fibers
which have been sized in order to provide coupling with the matrix.
These glass fibers are denoted "GF" in table 2 below.
[0129] The biobased reinforcements tested are: [0130] cellulose
microfibrils (denoted "cellulose" in table 2 below) sold by the
company Rettenmaier under the trademark Arbocel.RTM.. The grade
chosen in this example is BWW40 consisting of more than 99% by
weight of cellulose; [0131] flax fibers (denoted "flax" in table 2
below) sold by the company Dehondt under the trademark Lintex.RTM..
The grade chosen in this example is M10F.
[0132] Before mixing, these biobased reinforcements are predried at
between 100.degree. C. and 110.degree. C. in an oven for 12 hours
under vacuum. Likewise, the granules of PA MXD.10, PA6 and PA11 are
predried at between 60.degree. C. and 80.degree. C. for 12 hours in
an oven under vacuum.
[0133] The mixtures of polyamides and of biobased reinforcements as
detailed in table 2 below are prepared in an Explore.RTM.
co-rotating twin-screw microextruder from the company DSM. This
tool consists of a thermoregulated mixing chamber equipped with 2
co-rotating screws. The products are introduced by means of a
sliding piston. The mixing chamber is equipped with a recirculation
channel and with a die that can be closed, which makes it possible
to recirculate the material for a fixed period of time. The die is
then opened and the material is collected in a chamber which is
also thermally regulated (heat gun). This heat gun is then
connected to a microinjector which makes it possible to mold ISO
527 1BA standardized dumbbell-shaped specimens by applying a cycle
of varying pressures and controlled molding times, like what is
commonly done with an injection-molding press. The mold is also
thermoregulated, which makes it possible to mold at varying
temperatures.
[0134] For the examples described below, the mixtures are prepared:
[0135] at a temperature between 190.degree. C. and 220.degree. C.
measured in the molten material for the mixtures comprising PA
MXD.10, or PA11, and natural reinforcements, and [0136] at a
temperature of 230.degree. C. measured in the molten material for
the mixtures comprising PA6 and natural reinforcements.
[0137] The biobased reinforcements and the polyamides are
introduced into the thermoregulated mixing chamber by means of the
sliding piston. The mixtures are prepared with a screw speed set at
100 rpm. The recirculation time chosen is 90 seconds. During the
injection, the heat gun is thermoregulated at a temperature similar
to the mixing temperature and the mold at between 40.degree. C. and
80.degree. C. The maximum pressure of the cycle is 16 bar. The
residence times in the mold are between 6 and 20 seconds.
[0138] The dumbbell-shaped specimens obtained from various
compositions of examples 3 and 4 in accordance with the invention
and of comparative examples E and F are then conditioned for 15
days at 23.degree. C. at a relative humidity of 50%.
[0139] The mechanical properties of these dumbbell-shaped specimens
after conditioning, in particular the values of the tensile moduli,
are evaluated by adhering to the protocol described in standard ISO
527 1BA. The tensile modulus values (MPa), the standard deviation
values and also the density values are given in table 2 below.
[0140] This table 2 also reports the tensile modulus values
(according to standard ISO 527 1BA) and density values recorded:
[0141] for comparative example C: on the technical sheet of the
Ultramid.RTM. B3EG3 (PA6+glass fibers) commercial grade from the
company BASF, [0142] for comparative example D: on a technical
sheet of a mixture of PA11 and glass fibers, manufactured by the
company Arkema France.
TABLE-US-00002 [0142] TABLE 2 Examples Comparative examples 3 4 C D
E F Polyamide MXD. 10 MXD. 10 PA6 PA11 PA11 PA6 (85% by weight)
Reinforcements cellulose flax GF GF flax flax (15% by weight)
Tensile 4000 4000 3500 3000 2000 1900 modulus (MPa) +/- standard
+/-500 +/-500 -- -- +/-500 +/-250 deviation Density 1.16 1.20 1.24
1.12 1.08 1.16
[0143] It is observed that the tensile moduli of examples 3 and 4
reach values which are at least equal to, or even greater than,
those of conditioned dumbbell-shaped specimens formed from PA6 and
glass fibers (comparative example C), for much lower densities.
[0144] Moreover, the tensile modulus values of example 4
(MXD.10+flax) are very much greater than those of comparative
example E (PA11+flax) and even remain greater than those of
comparative example D (PA11+glass fibers).
[0145] Finally, the tensile modulus values of example 4
(MXD.10+flax) are also very much greater than those of comparative
example F (PA6+flax).
Example 5 and Comparative Examples G to K
Polyamides with 30% by Weight of Reinforcements
[0146] Various compositions comprising 70% by weight of a polyamide
and 30% by weight of reinforcements were prepared from the products
indicated hereinafter.
[0147] The polyamides used are the following: [0148] the polyamide
MXD.10 (Mp of 193.degree. C.) is identical to that of examples 1 to
4, [0149] the polyamide 6 (PA6, Mp of 220.degree. C.) corresponds
to the Ultramid.RTM. B36 commercial grade from the company BASF,
[0150] the polyamide 11 (PA11, Mp of 187-191.degree. C.)
corresponds to the Rilsan.RTM. BMNO commercial grade manufactured
by the company Arkema France.
[0151] The melting points Mp mentioned above were measured by DSC
according to standard ISO 11357.
[0152] The non-biobased reinforcement is made up of the same sized
glass fibers mentioned for comparative examples C and D described
above. These glass fibers are denoted "GF" in table 3 below.
[0153] The flax fibers (denoted "flax" in table 3 below) are the
same as those already used in example 4 and comparative examples E
and F.
[0154] The protocol for preparing the compositions and for
producing the dumbbell-shaped specimens which is described for
examples 3 and 4 and comparative examples E and F is reproduced,
but with 30% by weight of biobased reinforcements in the dry
mixture before introduction into the microextruder, the granules of
polyamides and also the reinforcements having been dried under the
same conditions as those previously described.
[0155] The dumbbell-shaped specimens obtained from various
compositions of example 5 in accordance with the invention and
comparative examples H and K are subsequently conditioned for 15
days at 23.degree. C. at a relative humidity of 50%.
[0156] The mechanical properties of these dumbbell-shaped specimens
after conditioning, in particular the tensile modulus values, are
evaluated by adhering to the protocol described in standard ISO 527
1BA. The tensile modulus values (MPa) and density values are given
in table 3 below.
[0157] This table 3 also reports the tensile modulus values
(according to standard ISO 527 1BA, except in the case of
comparative example G) and density values recorded: [0158] for
comparative example G: in example (9) of document EP 0 960 162 (it
being specified that the tensile modulus measurement is given
according to standard DIN 53455); [0159] for comparative example I:
on the technical sheet of the Rilsan.RTM. BZM30 O TL grade
(PA11+glass fibers) sold by the company Arkema France; [0160] for
comparative example J: on the technical sheet of the Ultramid.RTM.
B3EG3 commercial grade (PA6+glass fibers) from the company
BASF.
TABLE-US-00003 [0160] TABLE 3 Example Comparative examples 5 G H I
J K Polyamide (70% MXD. 10 PA11 PA11 PA11 PA6 PA6 by weight)
Reinforcements flax long flax GF GF flax (30% by weight) flax
Tensile modulus 6000 4050 3500 5300 6200 3300 (MPa) +/- standard
+/-500 +/-500 +/-500 deviation Density 1.20 -- 1.13 1.26 1.37
1.22
[0161] It is observed that the tensile modulus for example 5
reaches a value comparable of conditioned dumbbell-shaped specimens
formed from PA6 and from glass fibers (comparative example J),
which are known to be particularly satisfactory in terms of
modulus, for a much lower density.
[0162] It is of course possible to adapt the choice of biobased
fibers to the mechanical properties, in particular of tensile
modulus and density, desired.
[0163] For a comparable nature and amount of biobased
reinforcements, the compositions according to the invention make it
possible to obtain a material which is much more effective in terms
of mechanical properties than a material based on PA11 or PA6.
Reference may in particular be made to example 5 and comparative
example H, in the case of PA11, and to example 5 and comparative
example K in the case of PA6.
[0164] In the case of a composition based on PA11, this observation
still remains valid, even if the biobased flax fibers are replaced
with an equivalent weight amount of glass fibers (see example 5 and
comparative example I).
* * * * *